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Published on: February 23, 2017
Microextraction across supported liquid membranes forced by pH gradients and electrical fields
Astrid Gjelstad1, Torill Marita Andersen, Knut Einar Rasmussen
1School of Pharmacy, University of Oslo, Oslo, Norway.
Journal of Chromatography. A
|May 25, 2007
Summary
Electrokinetic migration (EMI) significantly enhances analyte extraction speed compared to passive diffusion (LPME) across supported liquid membranes (SLMs). This advancement offers a promising approach for rapid, miniaturized sample preparation and selective analyte isolation.
Area of Science:
- Analytical Chemistry
- Separation Science
- Membrane Technology
Background:
- Supported liquid membranes (SLMs) are utilized for analyte extraction.
- Passive diffusion (LPME) and electrokinetic migration (EMI) are two distinct mass transfer mechanisms applicable to SLMs.
Purpose of the Study:
- To compare the efficiency of passive diffusion (LPME) and electrokinetic migration (EMI) for basic analyte extraction across SLMs.
- To evaluate the potential of EMI for miniaturized sample preparation and selective extraction.
Main Methods:
- Analyte extraction was performed using a polypropylene hollow fiber SLM impregnated with 2-nitrophenyl octylether.
- Passive diffusion experiments (LPME) utilized a pH gradient with alkaline samples and acidic acceptor solution.
- Electrokinetic migration experiments (EMI) employed an electrical field with acidic samples and acidic acceptor solution.
Main Results:
- EMI demonstrated significantly improved extraction kinetics compared to LPME, with speed enhancements ranging from 6 to 17 fold.
- The speed advantage of EMI was particularly pronounced for small sample volumes (150 microl).
- EMI exhibited compound-dependent extraction rates, suggesting potential for controlled selectivity.
Conclusions:
- Electrokinetic migration (EMI) offers a substantial improvement in extraction speed over passive diffusion (LPME) for supported liquid membrane applications.
- EMI is a promising technique for developing miniaturized sample preparation methods.
- The compound-dependent extraction rates in EMI allow for tunable selectivity based on extraction time.
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